Stabilization of dichlorobutadiene resins



Patented July 4, 1 950 STABILIZATION OF DICHLOROBUTADIENE Y RESINS j f Eugene P. Stefl, Cuyahoga Falls, and Lloyd 0.

Bentz, Akron, Ohio, assignors to The Firestone Tire & Rubber Company, Akron, Ohio, a cor-'- poration of Ohio No Drawing. Application April 8, 1949, Y 1

Serial No. 86,406 v e v 8 Claims. (Cl. 260-4535) This invention relates to the stabilization, against discoloration and other deterioration by light and oxidation, of resinous polymers and copolymers of 2,3-dichloro-1,3-butadiene, hereinafter referred to, for brevity, as dichlorobutadiene. In general, the invention is based upon the discoverey that the resistance to light of these polymers and copolymers may be greatly enhanced by the addition thereto of 4-alkylphenyl salicylates in which the alkyl group contains from 9 to 12 carbon atoms.

THE DICHLOROBUTADIENE RESINS Referring first to the dichlorobutadiene polymers which may be stabilized in accordance with this invention, this compound has been polymerized heretofore to yield products aptly described as hard, infusible and insoluble. While such refractory resins may be stabilized in accordance with this invention, it has been discovered by an associate of the present applicants that the intractable nature of'the earlier dichlorobutadiene polymers is due to their excessive molecular weights and to a slight crosslinking which becomes significant at such high molecular weights. It has further been discovered by said associate that, providing the polymers of dichlorobutadiene are prepared in such a manner that their molecular weight corresponds to an intrinsic viscosity of from.0.1 to 1.5, the polymers arefusible to yield fluid melts, are soluble in hot solvents and have crystalline properties similar to those of the nylon and vinylidene chloride resinsi. 9., they may be extruded and cold-stretched to yield filaments, cordage etc., having excellent strength and flexibility and exhibiting oriented-crystalline X- ray patterns. These latter resins are clearly of greattechnical merit, and accordingly the invention is more particularly directed to the stabilization of such crystalline resins. However, it is tobe understood that any polymers or copolymers of dichlorobutadiene (whether or not crystalline as above described) containing a sumcient amount of dichlorobutadiene (say from about 25% to based on the total weight of resin) so that failure thereof under exposure to light'occurs by mechanisms involving the polydichlorobutadiene structure, may be stabilized in accordance with this invention.

Some techniques which have been found to yield polymers 0f dichlorobutadiene having an intrinsic viscosity range of from 0.1 to 1.5 are:

1.'A restrained chlorination of any infusible polymer or copolymer of dichlorobutadiene prepared in" accordance with the prior art; the chlorine uptake being strictly confined to the range 2-10%, and preferably 3 5%, based on the weight of polymer. This degree of chlorination does not appear'to alter the essential polymeric chain, but merely breaks up excessively long molecules, and the cross-linkages and side-structure attendant thereon.

2 .;;:'J,he use of --modifying agents, as the term is used in the synthetic rubber industry, to inolude certain polymerization-controlling substances, such as .lauryl mercaptan, butyl mercaptan, thiophenols, hexamethylene dimercaptan, diisopropyl xanthogen disulfide. The inclusion, in thepolymerization mass, of from 0.5 to 3.0%, or' in the case of some of the less powerful modifiers, as high as 15% of these modifiers, based on the weight of monomers (including com'onomers' as detailed below) will develop highly crystalline properties in the resultant resins. This technique is applicable to solution, emulsion or mass polymerization. Recommended amounts of the various types of modifiers areas follows.

Table I I a I Amount to Type of Modifier be used 1 Aryl mercaptans (containingSH groups directly 0.05 to 2.0

attached to aromatic nuclei) Aliphatic, cycloaliphatic, and aralipliatic mercaptans (containing from 1 to 8 carbon atoms) .5 to 5.0 Aliphatic, cycloaliphatic and araliphatic mercaptans (containing from 9 to 20 carbon atoms) 2 to 15 Percent, based on weight of dichlorobutadiene in polymerization mass u 3. Polymerization in non-reacting organic solvents, e. g. toluene, benzene, methanol, ethanol, ether, hexane, etc., in concentrations from about to about 60%, based on the total weight of solvent and dichlorobutadiene, at relatively elevated temperatures on the order of from about 40 to about 100 0., and in the presence of from about 0.1% to 5.0%, based on the total weight of polymerization mass, of a peroxidic catalyst such as benzoyl peroxide.

4. Polymerizing dichlorobutadiene or mixtures thereof with copolymerizable compounds in solution in organic solvents at temperatures in excess of 120 C., in the presence of inhibitors such as p-cresol employed to'the extent of about 1%,- based on the weight of 'dichlorobutadiene';

Of all of these techniques, that outlined under (2) is the most practical and reliable for the manufacture of resins for extrusion and orienta: tion into filaments, to the stabilization of which the present invention is of especial application.

As noted above, the present invention may be 100%, based on the weightof resin) such that-- the mechanism of degradation thereof contributes substantially to the ultimate failure of the resin. It is understood that,-ifthe resin-is to be of the fusible, crystalline type, it must not contain more than about2%of a cross-linking comonomer (i. e'., a plurally unsaturated co-" monomer in which the ethylenic groups are not conjugated or cross-conjugated) nor morethan about 10-15% of anyother comonomer'. These last two restrictions do not apply; if fusible, crystalline resins are not desired. Suitable noncrosslinking comonomers are exemplified in vinyl compounds on the order ofvinyl chloride, vinyl acetate," vinyl ethyl ether, vinyl p-chloroethyl ether, vinyl higher fatty ethers, vinyl phe'rllvl ether, etc.; vinyl ketones such as vinyl methyl ketone, methyl isopropenyl ketone', vinyl phenyl ketone, etc., cyclic vinyl compounds such asstyrene, a-methyl styrene, nuclearly chlorinatedstyrenes, p-vinyl benzoic acid, ,s-vinyl naph thalene, vinyl benzoate, vinyl carbazole, various vinyl pyridines, and the like; acrylic and substituted acrylic compounds such as methyl acrylate, methyl methacrylate, vinyl furane, ethyl chloroacrylate, methacrylonitrila. chloroacrylonitrile, acrylonitrile and the like; vinylidene halides such. as vinylidene chloride, vinylidene" bromide, 1-fluoro-1-chloroethylene; 1,1-dichloro-2,Z-difluoro-ethylene; compounds bearing an active cyclic unsaturated carbon atom such as coumarone, indene, 4-methylene-L3-dioxolane, substituted derivatives of this material, and the like. Examples of suitable conjugated and cross-conjugated copolymerizable compounds are butadiene, cyclopentadiene, choloroprene, 1-

chlorobutadiene, isopre'ne, 2,3-dimethyl buta-Q diene-1,3, piperylene, 2-methyl pentadiene, etc.

THE {LEALKYLPHENYL SALICYLATES The 4-alkylphenyl salicylates employetl -as-sta 4 bilizers in accordance with this invention may be any compounds having the formula (Alkyl group containing 9 to 12 carbons) in which formula the substituent indicated by the brackets is, as indicated, any alkyl group of any configuration containing from 9 to 12 carbon atoms. The 4-alkylphenyl salicylates in which the alkyl group at the 4-positionsin the phenyl groups contain from 1 to 8"carbon'atoms provide only mediocre stabilizing action in dichlorobutadiene resins. However, beginning at compounds containing 9 carbon atoms in the alkyl group; the stabilizing action abruptly becomes of a very high order. This high degree of stabilization is also characteristic of the compounds containing. 10 and-'11 carbon atoms in the alkyl groups;- The peak appears to have been passed at theoompoundscontaining l2-carbon atoms in the alkyl groups as these compounds are definitely; though slightly, inferior to those in which the alkyl groups contain from 9 to '11 carbon atoms.- Nevertheless, the compounds containing 12 carbon atoms in the alkyl groups are distinctly superior to" compounds containing. from 1 to 8 carbon atoms, ormore thanlz carbon atoms,:. and hence are to be included i'n-the scope of this iii ventio'n; The degree' of stabilizin'g effectiveness Of' any Of the 4-a1k'y1phel'iyl' s'alicylat'es ap ears to' be almost exclusively at functionof the number of" carbon atoms in the alkyl group, and to be largely"independent of" the configuration of that alk'yigroup: parallel tests with various isomeric" 4'-alkylphe'riyl s'alic'ylates aLllcbntai'ning the same" number of carbonatoms'in the alkyl groups give and the like. It' is to beiundersto'od', of'course,- that" there maybe employed mixtures" of 1 various i-alkylphenyl salicylatespomingi under the-formula as: above described. For? instance there* may beei'nployed salicylates of phenolwhi'ch has been allrylat'e'd in" the position' with unsaturated petr'ole'u'iii frac't ibnfs comprising mbnoiilefins contaiiiiri'g trdm' 9 'to- 12- carbon atoms; likewise tl-iere' may be employed" s'alicylatesof; phenols 4--alkylated iiiith monoolefin=dirnera trimer's and totramers'i for'iiistance the mixe d 'no'nenes"obtained by" trimeri'zation of propene, themixeu dodecene's' obtained by trimer'izationof butehe; the mixed" dodec'enes obtained by'tetrameriaation ofpropene, or themixed dodece'nes' obtainedby trimeri'zation of isobutene; etc.

- omingnow wtneamount of the e-alkylphenyl' salicylate to be added to the dichlorobutadiene necessary and wasteful. All of the foregoing percentages are given on the basis of the weight of the resin.

With the foregoing general discussion in mind, there are given herewith detailed examples of the practice of this invention. All parts given are by weight.

EXAMPLE A. Prepa ation'of 4-alkylphenyl salicylates Selected -alkylphenol (per Table II) gram-moles 0.5 Salicylic acid do 0.5 Phosphorus oxychloride do 0.16 Benzene ml 200 The filtered benzene solution was washed successively with portions of distilled water, 5% sodium hydroxide aqueous solution, and finally again with distilled water. The benzene was then removed by distillation, and the reaction mass fractionally distilled under reduced pressure. Particulars of the several runs are set forth in Table 11 below.

B. Preparation of 2,3-"dichZoro-1,3-butadiene polymers Parts Distilled water 330 2,3-dichloro-1,3-butadiene 100. Alkyl sodium sulfonates 1 1.0 Potassium persulfate .02 0.15

Thiophenol 1MP189EF, manufactured by E. I. du Pont de Nemours & Co. Sodium salts of the products of sulfonatlon of to 16 carbon-atom parafifins under exposure to ultraviolet light. Free of electrolytes. The above ingredients were charged under anerobic conditions into a polymerization vessel and agitated at 3040 C. for 24. hours. The resultant latex was coagulated by addition of methanol, the coagulum dewatered by filtration, washed with water on the filter, and dried. The resultant pulverulent resin was employed as a base resin for stabilization tests as described hereinafter. This resin had an intrinsic viscosity, measured in ortho dichlorobenzene at 110 0., of 0.43.

C. Preparation of stabilization test specimens Parts- Dichlorobutadiene polymer (prepared as described under B above) 100 4-alkyl salicylate (per Table II) 2, 3, 4 or 6 Acetone I A series of stabilization tests was run, using various 4-alkylphenylsalicylates (both within and without the scope of this invention) in the various proportions indicated in thefabove recipe and set forth in Table 11 hereinafter. In each test, the selected l-alkylphenyl salicylate, in the selected amount, and the acetone were dissolved together, the .dichlorobutadiene .polymer, was added to the solution and, the entire mixture was thoroughly worked together. The mixture was then spread out into a thin layer and. freed of the acetone by application of gentle heat.

One-half gram of the blended resin and plasticizer was poured onto a sheet of aluminum foil to form a conical pile, a second sheet of aluminum foil placed on the pile to cover the same, and the assembly placed in a laboratory'press having flat parallel platens heated'to 180 C. The platens were quickly closed on the'assembly, and left in light contact therewith for 10 seconds, after which a total load of 2460 pounds was applied to the platens and maintained for 30 seconds. The pres was then quickly opened, the assembly removed and quenched in cold water and the foil sheets peeled oif from the resultant fused plaque (usually about .005 inch thick) of resin and stabilizer. From this plaque were cut test specimens'Z inches long and .25 inch wide, which were subjected for varying periods of time to a light aging test as described below.

Exposure of test specimens The test specimens prepared as above described were then subjected to exposure for various eriods of time in a test substantially identical with the A. S. T. M. test D620-45T. For this test there is provided a General Electric s-unlamp, Model BM12 equipped with a reflector approximately 15 inches in diameter at the lower rim, with a General Electric S-l bulb which has been in operation at least 50 hours and less than 550 hours. The 8-1 bulb consists of a. combination tungsten filament and mercury are enclosed in a Corex D glass envelope which absorbs most of the ultraviolet radiation below 2800 A. The bulb is rated at 400 watts and operating voltage is maintained at :2 volts.

There is provided a circular plane turntable 17 inches in diameter revolving at 15 R. P. M. upon an axis through its center and perpendicular to its plane. The lam i mounted coaxially with said axis, with the bottom of the bulb 7 inches from the center of the turntable. The test specimens are mounted fiat on a white circular cardboard inch thick and 15 inches in diameter placed on the turntable concentric therewith. The specimens (9, large number are run simultaneously) are disposed radiallyupon the cardboard, with their inner ends on a radius 3% inches from the center thereof. A circular cover card 4%. inches in diameter is mounted on top of the specimens concentric with the turntable so as to cover the innermost half of the specimens.

At the end of the periods of exposure of the test specimens, they were removed and subjectively rated as to color by comparison with a series of standard colored specimens ranging from water-white to dark brown and arbitrarily rated from 0 for water-white to 10 for dark brown. Following are the'results of these tests.

Table II .Phenyl Salieylate Used Color Ratingof test Plaque at the End of- Fractionation of Amount Product St lsiied Ram a 128 I011 f f g gfig g Test, parts 20 24, 7 40 42 so 72 so 9o 96 120 144 185 substitutedin Hmsition Temp. 81111 by wt. hrs. hrs. hrs. hrs. hrs. hrs. hrs. hrs. hrs. hrs. hrs. hrs.

gfi ig apparatus (mm. of Hg) Unsubstituted phenol 3 '1 Methyl 3 2 Ethyl 132 0.08 a 3 IsopropyL 3 4 t-Buty 3 5 sec-Amyl 3 6 t-Amyl 3 7 hexyl' 3 8 tt octy 3 9 mixedv ny General product. 0.20 3 10 Fraction I 0.10 3 11 Fraction II 157-161 0. 10 3 12 Fraction III. 162 O. 10 3 13 Fraction IV. 162-166 0. 10 3 14 Fraction IV 166 0. l0 3 15 Fraction V L. 100 .002 3 16 Fraction VI 110 002 3 17 Fraction VII 120 .001 3 l8 Fraction VIII 140 001 3 19 Erection IX .150 .001 g 211] 3 22 Fractions V IX g 2 Mixed'4-decylphenols: 1

Fraction 130-152 0.10 3 '25 Fraction B 152-160 0.10 3 26 Fraction C 160-164 0.10 3 2? Fraction D 164-166 0. l0 3 0 28 Mixed dodecyl phenols 98-100 0. 09 1; 0+ 29 0+ 30 1 Containing mixed hexyl groups derived from a mixture of o carbon olefines.

Boiling range of the alkylated phenol l55165 C. at mm.

1 Containing mixed nonyl groups derived from mixed noncncs produced by trimerization of propene.

Ofiered-by Sharples Chemicals Inc. as 'p-tert-hexyl phenol."

Contains substantially all possible isomers, no isomer being present to the extent of more than 15%. Boiling-range of phenols 295-304" 0., specificgravity20l20 0.968, up 1.517.

Offered by Sharples Chemicals Inc. as nonyl phenol.

3 These fractions were obtained in a short-path or so-called molecular still.

4 Containing mixed decyl groups derived from a mixture of IO-carbon olefins. Containing mixed dodecyl groupsderived irommnred dodeccnes produced by tetramerlzation of propene.

Ofiered by Sharples Chemicals Inc. as "deeyl phenol." Ofiered by Sharples Chemicals Inc. as dodecyl phenol," boiling range BIO-335 0., specific gravity 20 O., 20 O. 093, up 1.517.

From the table, it will be evident that the lower -alkylphenyl salicylates containing from one to eight carbon atoms in the alkyl group (Items Nos. 1-9) have at most only mediocre stabilizing ability. However, beginning with the alkyl salicylates containing nine carbon atoms to which the present invention relates, an abrupt and remarkable improvement in the stabilizing effectiveness will be noted (Items Nos. 10-24). The 4-decyl phenyl salioylates (Items Nos. -28) provide the same high degree of stabilizing action. The 4-dodecyl phenyl salicylate (Items Nos. 29 and provides a somewhat less effective stabilizing action, although the protection afforded is still good. The stabilizing action appears to be a, function primarily of the number of carbon atomsin the alkyl group on the 4-position, and not to depend greatly on the configuration of the alkyl group itself, note that the different isomers (Items Nos. 10-22 and Items Nos. 25-28) of a given compound all exert approximately the same stabilizing action.

From the foregoing general discussion and detailed specific examples, it will be evident that this invention provides novel and highly effective agents for stabilizing the dichlorobutadiene resins. The stabilizers of this invention may readily be synthesized from cheaply and readily procurable starting materialsand entail no special difficulties in compounding and use. The stabilizers are non-toxic and, so far as has been observed, have no irritating efiect on the skin.

What is claimed is:

1. A light-stable composition of matter comprising .(A) a resin selected from the group consisting of polymers of 2,3-dichloro-1,3-butadiene and copolymers thereof with other unsaturated compounds copolymerizable therewith containing at least 25% of 2,3-dichloro-1,3-butadiene eopolymerized therein, together with (B) from 0.5% to 20%, based on the weight of said resin, of a 4-a-lkylphenyl salicylate in which the alkyl group contains from 9 to 12 carbon atoms.

2. A light-stable composition of matter comprising (A) a resin selected from the group consisting of polymers of '2,3-dichlor0-1,3-buta.diene and copolymers thereof with other unsaturated compounds copolymerizable therewith containing at least 25% of 2,3-dichloro-l,3-butadiene copolymerized therein, together with (B) from 0.5% to 20%, based on the weight of said resin, of a -nonylphenyl salicylate.

3. A light-stable composition of matter comprising (A) a resin selected from the group consisting of polymers of 2,3-dichloro-1,3-butadiene and 'copolymers thereof with other unsaturated compounds copolymerizable therewith containing at least 25% of 2,3-dichloro-l,3-butadiene copolymerized therein, together with (B) from 0.5% to 20%, based on the Weight of said resin, of a mixture of l-nonylphenyl salicylates in which the nonyl groups are derived from the mixed nonenes produced by trimerization of propene.

4. A light-stable composition of matter comprising (A) a resin selected from the group consisting of polymers of 2,3-dichloro-1,3-butadiene and copolymers thereof with other unsaturated compounds copolymerizable therewith containing at least 25% of v2,3-dichloro-l,3-butadienc 9 copolymerized therein, together with (B) from 0.5% to 20%, based on the weight of said resin, of a 4-decylphenyl salicylate.

5. A light-stable composition of matter comprising a polymer of 2,3-dichloro-1,3-butadiene having an intrinsic viscosity from 0.1 to 1.5, together with from 0.5% to 20%, based on the weight of said polymer, of a 4-a1ky1phenyl salicylate in which the alkyl group contains from 9 to 12 carbon atoms.

6. A light-stable composition of matter comprising a polymer of 2,3-dichloro-1,3-butadiene having an intrinsic viscosity of from 0.1 to 1.5, together with from 0.5% to 20%, based on the weight of said polymer, of a -nonyl phenyl salicylate.

7. A light-stable composition of matter comprising a polymer of 2,3-dichloro-1,3-butadiene having an intrinsic viscosity of from 0.1 to 1.5,

together with from 0.5% to 20%, based on the 20 2,445,739

10 weight of the polymer, of a mixture of 4-nonyl phenyl salicylates in which the nonyl group are derived from the mixed nonenes produced by trimerization of propene.

8. A light-stable composition of matter comprising a polymer of 2,3-dich1oro-1,3-butadiene having an intrinsic viscosity of from 0.1 to 1.5, together with from 0.5% to 20%, based on the weight of said polymer, of a 4-decyl phenyl sali- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Rowland et a1 July 20, 1948 Number Certificate of Correction Patent No. 2,514,216

It is hereby certified above numbered pa Column 4, lines 4 to 8 form to th EUGENE P. ST

that error appears tent requi ing correctlon as 13' inclusive, for

July 4,1950

EFL ET AL.

in the printed specification of the ollows:

(Alkyl group containing 9 to 12 carbons) read mm group containing a to 12 carbons) '0c 0Q in the second and fifth footn n 1.517 read n 1.517

and that the said Letters Patent shoul same may con Signed and sealed e record of the cas this 26th day of June, A.

otes under Table II, for

d be read as corrected above, so that the e in the Patent Oflice. D. 1951.

THOMAS E. MURPHY, 

1. A LIGHT-STABLE COMPOSITION OF MATTER COMPRISING (A) A RESIN SELECTED FROM THE GROUP CONSISTING OF POLYMERS OF 2,3-DICHLORO-1,3-BUTADIENE AND COPOLYMERS THEREOF WITH OTHER UNSATURATED COMPOUNDS COPOLYMERIZABLE THEREWITH CONTAINING AT LEAST 25% OF 2,3-DICHLORO-1,3-BUTADIENE COPOLYMERIZED THEREIN, TOGETHER WITH (B) FROM 0.5% TO 20%, BASED ON THE WEIGHT OF SAID RESIN, OF A 4-ALKYLPHENYL SALICYLATE IN WHICH THE ALKYL GROUP CONTAINS FROM 9 TO 12 CARBON ATOMS. 